2._CRD Background_NN1 and_CJC motivation_NN1 
This_DT0 section_NN1 provides_VVZ a_AT0 brief_AJ0 summary_NN1 of_PRF the_AT0 basic_AJ0 characteristics_NN2 of_PRF baroclinic_AJ0 waves_NN2 in_PRP the_AT0 northern_AJ0 hemisphere_NN1 ._SENT We_PNP limit_VVB the_AT0 discussion_NN1 to_PRP results_NN2 derived_VVN from_PRP observations_NN2 ,_PUN including_PRP those_DT0 obtained_VVN through_PRP data_NN0 assimilation_NN1 ._SENT See_VVB Barnes_NP0 et_NP0 al._NP0 (_PUL 2017_CRD )_PUR for_PRP a_AT0 comprehensive_AJ0 review_NN1 of_PRF both_DT0 observations_NN2 and_CJC numerical_AJ0 simulations_NN2 of_PRF baroclinic_AJ0 waves_NN2 ._SENT This_DT0 section_NN1 also_AV0 illustrates_VVZ the_AT0 limitations_NN2 of_PRF MCS_NN2 limb_NN1 profiles_NN2 for_PRP research_NN1 in_PRP this_DT0 area_NN1 ._SENT 
The_AT0 Viking_NN1 Landers_NN2 monitored_VVD the_AT0 atmosphere_NN1 of_PRF Mars_NP0 at_PRP two_CRD locations_NN2 in_PRP the_AT0 northern_AJ0 hemisphere_NN1 ,_PUN providing_VVG a_AT0 multi-year_AJ0 record_NN1 of_PRF pressure_NN1 and_CJC temperature_NN1 along_AVP with_PRP more_DT0 limited_AJ0 measurements_NN2 of_PRF winds_NN2 ._SENT This_DT0 led_VVD to_PRP numerous_AJ0 advances_NN2 in_PRP our_DPS understanding_NN1 of_PRF Martian_AJ0 weather_NN1 and_CJC climate_NN1 (_PUL Zurek_NP0 et_NP0 al._NP0 ,_PUN 1992_CRD )_PUR ._SENT In_PRP particular_AJ0 ,_PUN eastward-traveling_AJ0 baroclinic_AJ0 waves_NN2 were_VBD observed_VVN for_PRP the_AT0 first_ORD time_NN1 (_PUL Ryan_NP0 et_NP0 al._NP0 ,_PUN 1978_CRD ;_PUN Barnes_NP0 ,_PUN 1980_CRD ,_PUN 1981_CRD ;_PUN Ryan_NP0 and_CJC Sharman_NP0 ,_PUN 1981_CRD ;_PUN Leovy_NP0 et_NP0 al._NP0 ,_PUN 1985_CRD )_PUR ,_PUN confirming_VVG predictions_NN2 by_PRP numerical_AJ0 models_NN2 (_PUL Leovy_NP0 and_CJC Mintz_NP0 ,_PUN 1969_CRD )_PUR ._SENT The_AT0 waves_NN2 appear_VVB in_PRP autumn_NN1 and_CJC winter_NN1 with_PRP typical_AJ0 periods_NN2 of_PRF 2_CRD –_PUN 8_CRD sols_NN2 and_CJC an_AT0 amplitude_NN1 in_PRP surface_NN1 pressure_NN1 of_PRF a_AT0 few_DT0 percent_NN0 ._SENT Amplitudes_NN2 are_VBB much_AV0 larger_AJC at_PRP 48_CRD °_NN0 N_ZZ0 (_PUL Lander_NN1 2_CRD )_PUR than_CJS at_PRP 22_CRD °_NN0 N_ZZ0 (_PUL Lander_NN1 1_CRD )_PUR ._SENT Subsequent_AJ0 missions_NN2 have_VHB shown_VVN that_CJT the_AT0 waves_NN2 have_VHB a_AT0 discernible_AJ0 effect_NN1 on_PRP surface_NN1 pressure_NN1 at_PRP 4.5_CRD °_NN0 S_ZZ0 in_PRP Gale_NP0 Crater_NP0 (_PUL Haberle_NP0 et_NP0 al._NP0 ,_PUN 2018_CRD )_PUR and_CJC at_PRP 4.5_CRD °_NN0 N_ZZ0 in_PRP Elysium_NP0 Planitia_NP0 (_PUL Banfield_NP0 et_NP0 al._NP0 ,_PUN 2020b_CRD )_PUR ._SENT 
The_AT0 MGS_NP0 TES_NP0 sounded_VVD the_AT0 atmosphere_NN1 of_PRF Mars_NP0 from_PRP summer_NN1 of_PRF MY24_NP0 through_PRP spring_NN1 of_PRF MY27_CRD (_PUL Smith_NP0 et_NP0 al._NP0 ,_PUN 2001_CRD ;_PUN Smith_NP0 ,_PUN 2004_CRD )_PUR ._SENT Temperature_NN1 profiles_NN2 retrieved_VVN from_PRP nadir_NN1 observations_NN2 have_VHB a_AT0 vertical_AJ0 resolution_NN1 of_PRF about_AV0 10_CRD km_NN0 and_CJC provide_VVB complete_AJ0 global_AJ0 coverage_NN1 at_PRP two_CRD local_AJ0 times_NN2 ._SENT This_DT0 space-time_AJ0 coverage_NN1 is_VBZ favorable_AJ0 for_PRP investigations_NN2 of_PRF transient_AJ0 eddies_NN2 ,_PUN and_CJC much_DT0 of_PRF what_DTQ is_VBZ known_VVN about_PRP this_DT0 subject_NN1 derives_VVZ from_PRP the_AT0 TES_NP0 data_NN0 ._SENT After_PRP Wilson_NP0 et_NP0 al._NP0 (_PUL 2002_CRD )_PUR reported_VVD initial_AJ0 results_NN2 from_PRP northern_AJ0 autumn_NN1 and_CJC winter_NN1 of_PRF MY24_NP0 ,_PUN Banfield_NP0 et_NP0 al._NP0 (_PUL 2004_CRD )_PUR methodically_AV0 analyzed_VVN TES_NP0 data_NN0 from_PRP MY24_CRD and_CJC 25_CRD ,_PUN solving_VVG for_PRP the_AT0 amplitude_NN1 ,_PUN period_NN1 ,_PUN and_CJC zonal_AJ0 wavenumber_NN1 of_PRF the_AT0 transient_AJ0 eddies_NN2 and_CJC mapping_VVG their_DPS three-dimensional_AJ0 spatial_AJ0 structure_NN1 and_CJC seasonal_AJ0 evolution_NN1 in_PRP both_DT0 the_AT0 northern_AJ0 and_CJC southern_AJ0 hemispheres_NN2 ._SENT Subsequent_AJ0 analyses_NN2 of_PRF TES_NP0 profiles_NN2 extended_VVD the_AT0 survey_NN1 of_PRF eddy_NN1 activity_NN1 in_PRP the_AT0 northern_AJ0 hemisphere_NN1 through_PRP MY26_CRD (_PUL Wang_NP0 ,_PUN 2007_CRD ;_PUN Wang_NP0 et_NP0 al._NP0 ,_PUN 2013_CRD )_PUR ._SENT Rather_AV0 than_CJS attempting_VVG to_TO0 synthesize_VVI the_AT0 results_NN2 from_PRP these_DT0 studies_NN2 ,_PUN we_PNP summarize_VVB basic_AJ0 properties_NN2 of_PRF the_AT0 transient_AJ0 eddies_NN2 in_PRP the_AT0 context_NN1 of_PRF subsequent_AJ0 work_NN1 by_PRP Lewis_NP0 et_NP0 al._NP0 (_PUL 2016_CRD )_PUR ,_PUN especially_AV0 as_CJS it_PNP applies_VVZ to_PRP low-altitude_AJ0 baroclinic_AJ0 waves_NN2 ._SENT 
Lewis_NP0 et_NP0 al._NP0 (_PUL 2016_CRD )_PUR investigated_VVD the_AT0 '_PUQ winter_NN1 weather_NN1 '_PUQ on_PRP Mars_NP0 through_PRP data_NN0 assimilation_NN1 ,_PUN using_VVG TES_NP0 retrievals_NN2 of_PRF temperature_NN1 and_CJC dust_NN1 opacity_NN1 to_TO0 guide_VVI a_AT0 General_AJ0 Circulation_NN1 Model_NN1 (_PUL GCM_NP0 )_PUR ._SENT The_AT0 reanalysis_NN1 relies_VVZ on_PRP the_AT0 simulated_AJ0 general_AJ0 circulation_NN1 and_CJC the_AT0 model_NN1 physics_NN1 to_TO0 determine_VVI the_AT0 vertical_AJ0 structure_NN1 of_PRF the_AT0 baroclinic_AJ0 waves_NN2 ,_PUN which_DTQ is_VBZ not_XX0 fully_AV0 resolved_VVN by_PRP TES_NP0 ._SENT We_PNP consider_VVB only_AV0 the_AT0 results_NN2 in_PRP the_AT0 northern_AJ0 hemisphere_NN1 ._SENT The_AT0 baroclinic_AJ0 waves_NN2 have_VHB zonal_AJ0 wavenumbers_NN2 of_PRF 1_CRD –_PUN 3._CRD The_AT0 temperature_NN1 field_NN1 of_PRF both_DT0 the_AT0 wave-1_CRD and_CJC wave-2_CRD modes_NN2 has_VHZ a_AT0 large_AJ0 amplitude_NN1 at_PRP the_AT0 surface_NN1 ,_PUN a_AT0 minimum_NN1 at_PRP a_AT0 pressure_NN1 of_PRF about_PRP 200_CRD Pa_NP0 ,_PUN and_CJC a_AT0 local_AJ0 maximum_NN1 at_PRP about_PRP 20_CRD Pa_NP0 ;_PUN the_AT0 temperature_NN1 field_NN1 of_PRF wave-3_AJ0 mode_NN1 is_VBZ largely_AV0 confined_VVN to_PRP pressures_NN2 exceeding_VVG 200_CRD Pa._NP0 The_AT0 amplitude_NN1 is_VBZ largest_AJS in_PRP early-to-mid_AJ0 autumn_NN1 (_PUL Ls_NP0 =_NP0 180_CRD –_PUN 240_CRD °_NN0 )_PUR and_CJC mid-to-late_AJ0 winter_NN1 (_PUL Ls_NP0 =_NP0 300_CRD –_PUN 360_CRD °_NN0 )_PUR near_PRP the_AT0 edge_NN1 of_PRF the_AT0 seasonal_AJ0 CO2_NN1 ice_NN1 cap._NN1 In_PRP all_DT0 3_CRD MYs_NN2 observed_VVN by_PRP TES_NP0 ,_PUN the_AT0 baroclinic_AJ0 waves_NN2 subside_VVB near_PRP the_AT0 winter_NN1 solstice_NN1 ._SENT This_DT0 "_PUQ solstitial_AJ0 pause_NN1 "_PUQ is_VBZ apparent_AJ0 only_AV0 at_PRP pressures_NN2 greater_AJC than_CJS about_PRP 300_CRD Pa_NP0 ,_PUN owing_VVG to_PRP the_AT0 presence_NN1 of_PRF a_AT0 different_AJ0 type_NN1 of_PRF transient_AJ0 eddy_NN1 at_PRP higher_AJC altitudes_NN2 in_PRP late_AJ0 autumn_NN1 and_CJC early_AJ0 winter_NN1 ._SENT The_AT0 solstitial_AJ0 pause_NN1 has_VHZ a_AT0 significant_AJ0 impact_NN1 on_PRP the_AT0 seasonal_AJ0 dust_NN1 cycle_NN1 :_PUN frontal_AJ0 and_CJC flushing_AJ0 dust_NN1 storms_NN2 ,_PUN which_DTQ are_VBB initiated_VVN by_PRP baroclinic_AJ0 waves_NN2 ,_PUN cease_VVB at_PRP about_PRP Ls_ZZ0 =_NN1 240_CRD °_NN0 and_CJC do_VDB not_XX0 resume_VVI until_CJS after_CJS about_PRP Ls_ZZ0 =_NN1 300_CRD °_NN0 (_PUL Wang_NP0 et_NP0 al._NP0 ,_PUN 2005_CRD ;_PUN Wang_NP0 ,_PUN 2007_CRD ;_PUN Wang_NP0 and_CJC Richardson_NP0 ,_PUN 2015_CRD )_PUR ._SENT 
Greybush_NP0 et_NP0 al._NP0 (_PUL 2019_CRD )_PUR used_VVD a_AT0 different_AJ0 type_NN1 of_PRF data_NN0 assimilation_NN1 in_PRP a_AT0 similar_AJ0 investigation_NN1 of_PRF baroclinic_AJ0 waves_NN2 at_PRP low_AJ0 altitudes_NN2 ._SENT In_PRP this_DT0 approach_NN1 ,_PUN the_AT0 output_NN1 from_PRP the_AT0 reanalysis_NN1 is_VBZ a_AT0 16-member_AJ0 ensemble_NN1 ,_PUN which_DTQ provides_VVZ information_NN1 about_PRP the_AT0 reliability_NN1 of_PRF the_AT0 results_NN2 :_PUN confidence_NN1 increases_VVZ as_PRP the_AT0 ensemble_NN1 spread_NN1 decreases_VVZ ._SENT When_CJS applied_VVN to_PRP TES_NP0 temperature_NN1 profiles_NN2 ,_PUN there_EX0 is_VBZ little_DT0 difference_NN1 among_PRP the_AT0 members_NN2 of_PRF the_AT0 ensemble_NN1 ,_PUN and_CJC the_AT0 ensemble_NN1 mean_VVB closely_AV0 resembles_VVZ the_AT0 results_NN2 obtained_VVN by_PRP Lewis_NP0 et_NP0 al._NP0 (_PUL 2016_CRD )_PUR ._SENT However_AV0 ,_PUN similar_AJ0 reanalysis_NN1 of_PRF MCS_NN2 temperature_NN1 profiles_NN2 yielded_VVD mixed_AJ0 results_NN2 ._SENT The_AT0 ensemble_NN1 does_VDZ not_XX0 converge_VVI consistently_AV0 ,_PUN owing_VVG to_PRP the_AT0 scarcity_NN1 of_PRF successful_AJ0 retrievals_NN2 at_PRP pressures_NN2 exceeding_VVG 350_CRD Pa_NP0 ,_PUN as_CJS discussed_VVN below_AV0 ._SENT This_DT0 implies_VVZ that_CJT the_AT0 information_NN1 contained_VVN in_PRP the_AT0 MCS_NN2 profiles_NN2 (_PUL version_NN1 5_CRD )_PUR is_VBZ not_XX0 sufficient_AJ0 to_TO0 support_VVI a_AT0 comprehensive_AJ0 investigation_NN1 of_PRF wave_NN1 activity_NN1 near_PRP the_AT0 surface_NN1 ._SENT 
MGS_NP0 radio_NN1 occultation_NN1 (_PUL RO_NP0 )_PUR profiles_NN2 of_PRF temperature_NN1 and_CJC geopotential_AJ0 height_NN1 provide_VVB additional_AJ0 information_NN1 about_PRP baroclinic_AJ0 waves_NN2 (_PUL Hinson_NP0 and_CJC Wilson_NP0 ,_PUN 2002_CRD ;_PUN Hinson_NP0 ,_PUN 2006_CRD ;_PUN Hinson_NP0 and_CJC Wang_NP0 ,_PUN 2010_CRD ;_PUN Hinson_NP0 et_NP0 al._NP0 ,_PUN 2012_CRD )_PUR ._SENT In_PRP particular_AJ0 ,_PUN the_AT0 vertical_AJ0 structure_NN1 of_PRF the_AT0 waves_NN2 can_VM0 be_VBI determined_VVN with_PRP sub-kilometer_NN1 resolution_NN1 ._SENT Fig._NN1 1_CRD shows_VVZ three_CRD examples_NN2 ._SENT In_PRP each_DT0 case_NN1 ,_PUN the_AT0 amplitude_NN1 in_PRP temperature_NN1 is_VBZ largest_AJS at_PRP about_PRP 600_CRD Pa_NP0 and_CJC it_PNP decreases_VVZ rapidly_AV0 at_PRP lower_AJC pressures_NN2 ._SENT This_DT0 type_NN1 of_PRF wave_NN1 structure_NN1 is_VBZ largely_AV0 inaccessible_AJ0 to_PRP MCS_NN2 limb_NN1 sounding_NN1 ._SENT Among_PRP the_AT0 100_CRD ,_PUN 000_CRD profiles_NN2 available_AJ0 at_PRP mid-to-high_AJ0 northern_AJ0 latitudes_NN2 during_PRP Ls_NP0 =_NP0 180_CRD –_PUN 360_CRD °_NN0 of_PRF MY30_NN0 ,_PUN fewer_DT0 than_CJS 20_CRD %_NN0 reach_VVB pressures_NN2 greater_AJC than_CJS 350_CRD Pa_NP0 ,_PUN as_CJS shown_VVN in_PRP Fig._NN1 1._CRD 
The_AT0 scarcity_NN1 of_PRF MCS_NN2 profiles_NN2 at_PRP low_AJ0 altitudes_NN2 is_VBZ a_AT0 serious_AJ0 impediment_NN1 to_PRP studies_NN2 of_PRF baroclinic_AJ0 waves_NN2 ._SENT We_PNP illustrate_VVB this_DT0 point_NN1 in_PRP Appendix_NN1 A_ZZ0 by_PRP extracting_VVG samples_NN2 of_PRF temperature_NN1 at_PRP 610_CRD Pa_NP0 from_PRP 1_CRD MY_DPS of_PRF MCS_NN2 profiles_NN2 and_CJC using_VVG the_AT0 procedure_NN1 described_VVN in_PRP Section_NN1 4_CRD to_TO0 search_VVI for_PRP waves_NN2 ._SENT (_PUL Initial_AJ0 results_NN2 from_PRP a_AT0 similar_AJ0 effort_NN1 were_VBD reported_VVN recently_AV0 by_PRP Banfield_NP0 et_NP0 al._NP0 (_PUL 2020a_NP0 )_PUR ._SENT )_PUR This_DT0 yielded_VVD some_DT0 tantalizing_AJ0 results_NN2 ,_PUN but_CJC there_EX0 is_VBZ a_AT0 major_AJ0 gap_NN1 in_PRP coverage_NN1 throughout_PRP polar_AJ0 night_NN1 and_CJC extending_VVG well_AV0 into_PRP the_AT0 surrounding_AJ0 baroclinic_AJ0 zone_NN1 ._SENT The_AT0 results_NN2 from_PRP limb_NN1 sounding_NN1 are_VBB not_XX0 sufficient_AJ0 to_TO0 meet_VVI our_DPS objectives_NN2 ,_PUN which_DTQ led_VVD us_PNP to_TO0 consider_VVI another_DT0 type_NN1 of_PRF MCS_NN2 observation_NN1 ._SENT 
3._CRD Observations_NN2 
This_DT0 investigation_NN1 relies_VVZ on_PRP data_NN0 from_PRP two_CRD infrared_AJ0 sounders_NN2 ,_PUN the_AT0 MRO_NN1 MCS_NN2 and_CJC the_AT0 MGS_NP0 TES_NP0 ._SENT The_AT0 data_NN0 sets_NN2 have_VHB similar_AJ0 coverage_NN1 in_PRP longitude_NN1 ,_PUN latitude_NN1 ,_PUN and_CJC local_AJ0 time_NN1 ._SENT There_EX0 is_VBZ no_AT0 overlap_NN1 in_PRP atmospheric_AJ0 measurements_NN2 by_PRP the_AT0 two_CRD instruments_NN2 ._SENT 
3.1_CRD ._SENT The_AT0 MRO_NN1 Mars_NP0 Climate_NN1 Sounder_NN1 
We_PNP examined_VVD MCS_NN2 data_NN0 acquired_VVD when_CJS the_AT0 instrument_NN1 was_VBD pointed_VVN at_PRP the_AT0 surface_NN1 and_CJC found_VVD that_CJT the_AT0 B1_AJ0 channel_NN1 is_VBZ the_AT0 best_AJS source_NN1 of_PRF information_NN1 about_PRP baroclinic_AJ0 waves_NN2 in_PRP the_AT0 northern_AJ0 hemisphere_NN1 ._SENT However_AV0 ,_PUN other_AJ0 channels_NN2 may_VM0 be_VBI needed_VVN when_CJS we_PNP extend_VVB the_AT0 analysis_NN1 to_PRP the_AT0 southern_AJ0 hemisphere_NN1 ,_PUN where_AVQ the_AT0 surface_NN1 pressure_NN1 is_VBZ generally_AV0 smaller_AJC than_CJS in_PRP the_AT0 north_NN1 ._SENT 
The_AT0 observations_NN2 used_VM0 here_AV0 come_VVI from_PRP Reduced_AJ0 Data_NN0 Records_NN2 (_PUL RDRs_NP0 )_PUR stored_VVN at_PRP the_AT0 Atmospheres_NN2 Node_NN1 of_PRF the_AT0 NASA_NP0 Planetary_AJ0 Data_NN0 System_NN1 (_PUL PDS_NP0 )_PUR ._SENT We_PNP consider_VVB only_AV0 data_NN0 acquired_VVN in_PRP a_AT0 uniform_AJ0 viewing_NN1 geometry_NN1 with_PRP MCS_NN2 pointed_VVN in_PRP the_AT0 forward_AJ0 direction_NN1 (_PUL 178_CRD °_NN0 <_NN1 azimuth_NN1 <_NN1 182_CRD °_NN0 )_PUR and_CJC viewing_VVG the_AT0 surface_NN1 at_PRP an_AT0 emission_NN1 angle_NN1 of_PRF about_AV0 60_CRD °_NN0 (_PUL 118_CRD °_NN0 <_NN1 elevation_NN1 <_NN1 123_CRD °_NN0 )_PUR ._SENT In_PRP addition_NN1 ,_PUN we_PNP exclude_VVB any_DT0 observation_NN1 performed_VVN under_PRP abnormal_AJ0 conditions_NN2 ,_PUN such_DT0 as_PRP when_AVQ the_AT0 spacecraft_NN0 was_VBD rolling_VVG or_CJC when_CJS MCS_NN2 was_VBD safing_AJ0 ,_PUN safed_AJ0 ,_PUN freezing_AJ0 ,_PUN frozen_AJ0 ,_PUN dumping_VVG ,_PUN or_CJC moving_VVG (_PUL as_CJS defined_VVN in_PRP the_AT0 PDS_NP0 documentation_NN1 for_PRP the_AT0 RDRs_NP0 )_PUR ._SENT 
The_AT0 information_NN1 extracted_VVN from_PRP the_AT0 RDRs_NP0 includes_VVZ the_AT0 calibrated_AJ0 B1_AJ0 radiance_NN1 ,_PUN the_AT0 time_NN1 of_PRF observation_NN1 (_PUL UTC_NP0 )_PUR ,_PUN and_CJC the_AT0 longitude_NN1 ,_PUN latitude_NN1 ,_PUN and_CJC local_AJ0 time_NN1 at_PRP the_AT0 observation_NN1 point_NN1 on_PRP the_AT0 surface_NN1 of_PRF Mars_NP0 (_PUL based_VVN on_PRP reconstructions_NN2 of_PRF spacecraft_NN0 position_NN1 and_CJC MCS_NN2 pointing_VVG direction_NN1 )_PUR ._SENT We_PNP computed_VVD Ls_NP0 for_PRP each_DT0 data_NN0 sample_NN1 using_VVG classical_AJ0 orbital_AJ0 elements_NN2 for_PRP Mars_NP0 ._SENT Observations_NN2 that_CJT meet_VVB all_DT0 criteria_NN2 mentioned_VVN above_AV0 are_VBB obtained_VVN routinely_AV0 as_PRP part_NN1 of_PRF the_AT0 standard_AJ0 MCS_NN2 observing_VVG sequence_NN1 (_PUL McCleese_NP0 et_NP0 al._NP0 ,_PUN 2007_CRD )_PUR ,_PUN providing_VVG regular_AJ0 coverage_NN1 of_PRF both_DT0 the_AT0 dayside_NN1 and_CJC the_AT0 nightside_NN1 as_CJS shown_VVN in_PRP Fig._NN1 2._CRD 
We_PNP used_VVD radiances_NN2 from_PRP detectors_NN2 B1_CRD –_PUN 10_CRD ,_PUN B1_CRD –_PUN 11_CRD (_PUL the_AT0 middle_AJ0 detector_NN1 )_PUR ,_PUN and_CJC B1_CRD –_PUN 12_CRD ;_PUN the_AT0 other_AJ0 18_CRD detectors_NN2 of_PRF the_AT0 B1_AJ0 channel_NN1 are_VBB ignored_VVN ._SENT The_AT0 brightness_NN1 temperature_NN1 is_VBZ computed_VVN from_PRP the_AT0 average_AJ0 radiance_NN1 in_PRP these_DT0 three_CRD detectors_NN2 using_VVG the_AT0 inverse_AJ0 Planck_NP0 function_NN1 for_PRP the_AT0 central_AJ0 wavenumber_NN1 of_PRF detector_NN1 B-11_CRD (_PUL 317.788_NN0 cm−1_CRD )_PUR ._SENT For_PRP example_NN1 ,_PUN Fig._NN1 3_CRD shows_VVZ the_AT0 variations_NN2 of_PRF brightness_NN1 temperature_NN1 with_PRP latitude_NN1 for_PRP the_AT0 observations_NN2 in_PRP Fig._NN1 2._CRD Atmospheric_AJ0 gases_NN2 are_VBB transparent_AJ0 at_PRP 32_CRD microns_NN2 ,_PUN so_AV0 the_AT0 emission_NN1 comes_VVZ primarily_AV0 from_PRP the_AT0 surface_NN1 with_PRP a_AT0 smaller_AJC contribution_NN1 from_PRP atmospheric_AJ0 dust_NN1 ._SENT Fig._NN1 3_CRD has_VHZ several_DT0 notable_AJ0 features_NN2 ._SENT First_ORD ,_PUN there_EX0 is_VBZ a_AT0 large_AJ0 day-night_AJ0 temperature_NN1 difference_NN1 (_PUL about_PRP 80_CRD K_ZZ0 )_PUR at_PRP low_AJ0 latitudes_NN2 ._SENT Second_ORD ,_PUN spatial_AJ0 variations_NN2 in_PRP surface_NN1 thermal_AJ0 inertial_AJ0 cause_NN1 substantial_AJ0 zonal_AJ0 variations_NN2 in_PRP nightside_NN1 temperature_NN1 at_PRP latitudes_NN2 south_NN1 of_PRF 50_CRD °_NN0 N_ZZ0 ._SENT Third_ORD ,_PUN there_EX0 is_VBZ a_AT0 strong_AJ0 meridional_AJ0 gradient_NN1 of_PRF brightness_NN1 temperature_NN1 at_PRP high_AJ0 latitudes_NN2 ,_PUN particularly_AV0 on_PRP the_AT0 dayside_NN1 ,_PUN where_AVQ the_AT0 temperature_NN1 decreases_VVZ from_PRP about_AV0 225_CRD K_ZZ0 at_PRP 60_CRD °_NN0 N_ZZ0 to_PRP less_AV0 than_CJS 170_CRD K_ZZ0 at_PRP 70_CRD °_NN0 N_ZZ0 ._SENT Finally_AV0 ,_PUN the_AT0 bimodal_AJ0 temperature_NN1 distribution_NN1 at_PRP latitudes_NN2 north_NN1 of_PRF about_AV0 70_CRD °_NN0 N_ZZ0 is_VBZ a_AT0 consequence_NN1 of_PRF zonal_AJ0 variations_NN2 in_PRP the_AT0 distribution_NN1 of_PRF CO2_AJ0 ice_NN1 (_PUL Calvin_NP0 et_NP0 al._NP0 ,_PUN 2015_CRD )_PUR ._SENT As_CJS we_PNP show_VVB in_PRP Section_NN1 5.4_CRD (_PUL Fig._NN1 11_CRD )_PUR ,_PUN a_AT0 baroclinic_AJ0 wave_NN1 is_VBZ present_AJ0 at_PRP the_AT0 time_NN1 of_PRF these_DT0 observations_NN2 ,_PUN with_PRP a_AT0 zonal_AJ0 wavenumber_NN1 of_PRF 2_CRD and_CJC an_AT0 amplitude_NN1 of_PRF 2_CRD –_PUN 3_CRD K_ZZ0 at_PRP 60_CRD –_PUN 75_CRD °_NN0 N_ZZ0 ._SENT 
We_PNP computed_VVD the_AT0 zonal-mean_AJ0 surface_NN1 temperature_NN1 at_PRP a_AT0 local_AJ0 time_NN1 of_PRF 15_CRD h_ZZ0 from_PRP B1_CRD measurements_NN2 such_DT0 as_PRP those_DT0 in_PRP Fig._NN1 3._CRD The_AT0 results_NN2 provide_VVB context_NN1 for_PRP interpreting_VVG some_DT0 aspects_NN2 of_PRF the_AT0 wave_NN1 measurements_NN2 ._SENT In_PRP particular_AJ0 ,_PUN the_AT0 150-K_AJ0 contour_NN1 gives_VVZ the_AT0 approximate_AJ0 location_NN1 of_PRF the_AT0 edge_NN1 of_PRF the_AT0 CO2_AJ0 ice_NN1 cap._NN1 (_PUL See_VVB Figs._NN2 6_CRD –_PUN 8_CRD ,_PUN below_AV0 ._SENT )_PUR 
Although_CJS it_PNP is_VBZ not_XX0 obvious_AJ0 from_PRP Fig._NN1 3_CRD ,_PUN the_AT0 B1_AJ0 channel_NN1 also_AV0 contains_VVZ valuable_AJ0 information_NN1 about_PRP baroclinic_AJ0 waves_NN2 at_PRP pressures_NN2 greater_AJC than_CJS 300_CRD Pa._NP0 Two_CRD aspects_NN2 of_PRF the_AT0 results_NN2 support_VVB the_AT0 conclusions_NN2 about_PRP the_AT0 identity_NN1 of_PRF the_AT0 wave_NN1 and_CJC its_DPS vertical_AJ0 location_NN1 :_PUN (_PUL 1_CRD )_PUR the_AT0 presence_NN1 of_PRF a_AT0 deep_AJ0 solstitial_AJ0 pause_NN1 ,_PUN as_CJS discussed_VVN in_PRP Sections_NN2 5.1_CRD and_CJC 6.2_CRD ;_PUN and_CJC (_PUL 2_CRD )_PUR the_AT0 strong_AJ0 resemblance_NN1 to_PRP baroclinic_AJ0 waves_NN2 observed_VVN by_PRP TES_NP0 at_PRP 610_CRD Pa_NP0 ,_PUN as_CJS discussed_VVN in_PRP Sections_NN2 5.3_CRD ,_PUN 5.4_CRD ,_PUN and_CJC 6.2_CRD ._SENT Results_NN2 derived_VVN through_PRP analysis_NN1 of_PRF MCS_NN2 temperature_NN1 profiles_NN2 also_AV0 support_VVB this_DT0 conclusion_NN1 ,_PUN as_CJS discussed_VVN in_PRP Appendix_NN1 A_ZZ0 ._SENT 
The_AT0 MCS_NN2 measurements_NN2 considered_VVN here_AV0 extend_VVB from_PRP Ls_ZZ0 =_NN1 329_CRD °_NN0 of_PRF MY28_CRD through_PRP Ls_ZZ0 =_NN1 90_CRD °_NN0 of_PRF MY34_NP0 ._SENT There_EX0 were_VBD no_AT0 planet-enshrouding_AJ0 dust_NN1 storms_NN2 (_PUL PEDS_NP0 )_PUR during_PRP this_DT0 period_NN1 ._SENT 
3.2_CRD ._SENT The_AT0 MGS_NP0 Thermal_AJ0 Emission_NN1 Spectrometer_NN1 
As_CJS part_NN1 of_PRF this_DT0 investigation_NN1 we_PNP also_AV0 analyzed_VVD temperatures_NN2 retrieved_VVN from_PRP TES_NP0 nadir_NN1 measurements_NN2 (_PUL Conrath_NP0 et_NP0 al._NP0 ,_PUN 2000_CRD ;_PUN Smith_NP0 ,_PUN 2004_CRD )_PUR ._SENT Like_PRP MCS_NN2 ,_PUN TES_NP0 provided_VVD daily_AJ0 global_AJ0 coverage_NN1 at_PRP two_CRD local_AJ0 times_NN2 ,_PUN but_CJC the_AT0 TES_NP0 coverage_NN1 differs_VVZ in_PRP several_DT0 respects_NN2 from_PRP that_DT0 shown_VVN in_PRP Fig._NN1 2._CRD First_ORD ,_PUN profiles_NN2 were_VBD obtained_VVN more_AV0 frequently_AV0 by_PRP TES_NP0 ,_PUN which_DTQ reduces_VVZ the_AT0 separation_NN1 in_PRP latitude_NN1 between_PRP successive_AJ0 measurements_NN2 ._SENT Second_ORD ,_PUN MGS_NP0 completed_VVD 12.6_CRD orbits_NN2 per_PRP sol_NN1 ,_PUN as_CJS compared_VVN with_PRP 13.2_CRD for_PRP MRO_NN1 ._SENT Finally_AV0 ,_PUN TES_NP0 sampled_VVD local_AJ0 times_NN2 of_PRF about_AV0 2_CRD and_CJC 14_CRD h_ZZ0 ,_PUN 1_CRD h_ZZ0 earlier_AV0 than_CJS MCS_NN2 ._SENT None_PNI of_PRF these_DT0 differences_NN2 is_VBZ important_AJ0 in_PRP the_AT0 context_NN1 of_PRF this_DT0 investigation_NN1 ._SENT 
TES_NP0 nadir_NN1 profiles_NN2 extend_VVB from_PRP the_AT0 surface_NN1 to_PRP the_AT0 10-Pa_AJ0 pressure_NN1 level_NN1 ;_PUN the_AT0 vertical_AJ0 resolution_NN1 is_VBZ about_AV0 10_CRD km_NN0 ._SENT For_PRP present_AJ0 purposes_NN2 it_PNP is_VBZ sufficient_AJ0 to_TO0 consider_VVI only_AJ0 temperature_NN1 measurements_NN2 at_PRP the_AT0 610-Pa_NN1 pressure_NN1 level_NN1 ,_PUN which_DTQ is_VBZ well_AV0 aligned_VVN with_PRP the_AT0 near-surface_AJ0 peak_NN1 in_PRP wave_NN1 amplitude_NN1 (_PUL see_VVB Fig._NN1 1_CRD )_PUR ._SENT In_PRP the_AT0 autumn_NN1 and_CJC winter_NN1 seasons_NN2 ,_PUN the_AT0 surface_NN1 pressure_NN1 in_PRP the_AT0 northern_AJ0 hemisphere_NN1 generally_AV0 exceeds_VVZ 610_CRD Pa_NN1 at_PRP mid-to-high_AJ0 latitudes_NN2 ,_PUN where_CJS the_AT0 wave_NN1 amplitude_NN1 is_VBZ largest_AJS ._SENT 
The_AT0 TES_NP0 measurements_NN2 used_VVN in_PRP this_DT0 investigation_NN1 extend_VVB from_PRP Ls_ZZ0 =_NN1 141_CRD °_NN0 of_PRF MY24_NP0 through_PRP Ls_NP0 =_NN1 72_CRD °_NN0 of_PRF MY27_CRD ._SENT One_CRD PEDS_NN2 occurred_VVN within_PRP this_DT0 period_NN1 ,_PUN in_PRP autumn_NN1 of_PRF MY25_NP0 ._SENT 
4._CRD Method_NN1 of_PRF analysis_NN1 
Several_DT0 methods_NN2 of_PRF analysis_NN1 have_VHB been_VBN used_VVN in_PRP previous_AJ0 investigations_NN2 of_PRF baroclinic_AJ0 waves_NN2 ,_PUN as_CJS reviewed_VVN by_PRP Barnes_NP0 et_NP0 al._NP0 (_PUL 2017_CRD )_PUR ._SENT We_PNP chose_VVD a_AT0 least-squares_NN2 method_NN1 for_PRP several_DT0 reasons_NN2 ._SENT First_ORD ,_PUN it_PNP can_VM0 be_VBI applied_VVN directly_AV0 to_PRP data_NN0 with_PRP irregular_AJ0 sample_NN1 spacing_NN1 in_PRP longitude_NN1 and_CJC time_NN1 of_PRF observation_NN1 ,_PUN which_DTQ makes_VVZ it_PNP easy_AJ0 to_TO0 combine_VVI data_NN0 from_PRP the_AT0 dayside_NN1 and_CJC the_AT0 nightside_NN1 ._SENT In_PRP addition_NN1 ,_PUN each_DT0 data_NN0 sample_NN1 can_VM0 be_VBI weighted_VVN according_VVG to_PRP its_DPS accuracy_NN1 ;_PUN equal_AJ0 weights_NN2 are_VBB used_VVN here_AV0 ,_PUN but_CJC we_PNP may_VM0 assign_VVI different_AJ0 weights_NN2 to_PRP data_NN0 from_PRP the_AT0 dayside_NN1 and_CJC the_AT0 nightside_NN1 in_PRP future_AJ0 work_NN1 ._SENT Finally_AV0 ,_PUN the_AT0 method_NN1 can_VM0 be_VBI applied_VVN directly_AV0 to_PRP data_NN0 sets_NN2 with_PRP occasional_AJ0 missing_AJ0 samples_NN2 ;_PUN no_AT0 special_AJ0 treatment_NN1 ,_PUN such_DT0 as_PRP interpolation_NN1 ,_PUN is_VBZ required_VVN ._SENT 
